Method of drilling from a shaft for underground recovery of hydrocarbons

ABSTRACT

The present invention discloses a selection process for installing underground workspace in or near a hydrocarbon deposit that is an appropriate workspace from which to drill, operate and service wells applicable to any of a number of methods of recovering hydrocarbons. The present invention includes a number of innovative methods for developing workspace for drilling from a shaft installed above, into or below a hydrocarbon deposit, particularly when the hydrocarbon reservoir is at significant formation pressure or has fluids (water oil or gases) that can enter the workspace. These methods can also be used for developing workspace for drilling from a tunnel installed above, into or below a hydrocarbon deposit. The present invention also discloses a procedure for evaluating the geology in and around the reservoir and using this information to select the most appropriate method of developing workspace for drilling from a shaft and/or tunnel.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 11/737,578 filed on Apr. 19, 2007, entitled “METHOD OF DRILLINGFROM A SHAFT FOR UNDERGROUND RECOVERY OF HYDROCARBONS” which claims thebenefits, under 35 U.S.C. §119(e), of U.S. Provisional Application Ser.No. 60/793,975 filed Apr. 21, 2006, entitled “Method of Drilling from aShaft” to Brock, Kobler and Watson; U.S. Provisional Application Ser.No. 60/868,467 filed Dec. 4, 2006, entitled “Method of Drilling from aShaft” to Brock, Kobler and Watson; and U.S. Provisional ApplicationSer. No. 60/867,010 filed Nov. 22, 2006 entitled “Recovery of Bitumen byHydraulic Excavation” to Brock, Squires and Watson, all of which areincorporated herein by these references.

Cross reference is made to U.S. patent application Ser. No. 11/441,929filed May 25, 2006, entitled “Method for Underground Recovery ofHydrocarbons”, which is also incorporated herein by this reference.

FIELD

The present invention relates generally to selection of a linedshaft-based and tunnel-based method and system for installing, operatingand servicing wells for recovery of hydrocarbons from pressurizedsoft-ground reservoirs, wherein the underground space is always isolatedfrom the formation.

BACKGROUND

Oil is a nonrenewable natural resource having great importance to theindustrialized world. The increased demand for and decreasing suppliesof conventional oil has led to the development of alternative sources ofcrude oil such as oil sands containing bitumen or heavy oil and to asearch for new techniques for continued recovery from conventional oildeposits. The development of the Athabasca oil sands in particular hasresulted in increased proven world reserves of over 170 billion barrelsfrom the application of surface mining and in-situ technologies. Thereare also large untapped reserves in the form of stranded oil depositsfrom known reservoirs. Estimates as high as 300 billion barrels ofrecoverable light and heavy oil have been made for North America.Recovery of stranded oil requires new recovery techniques that canovercome, for example, the loss of drive pressure required to move theoil to nearby wells where it can be pumped to the surface. These twosources of oil, oil sands and stranded oil, are more than enough toeliminate the current dependence on outside sources of oil and, inaddition, require no substantial exploration.

Shaft Sinking

Shaft-sinking or shaft-drilling are well-developed areas of civil andmining construction. Applications in civil construction include forexample ventilation shafts for transportation tunnels, access shafts forwater drainage and sewage system tunnels and Ranney wells for recoveringfiltered water from aquifers. Applications in mining include for exampleventilation and access shafts for underground mine works. Shafts havebeen sunk in hard rock and drilled or bored into soft-ground.Soft-ground shafts are commonly concrete lined shafts and are installedby a variety of methods. These methods include drilling and boringtechniques often where the shaft is filled with water or drilling mud tocounteract local ground pressures. There are casing drilling machinesthat use high torque reciprocating drives to work steel casing into theformation. There are also shaft sinking techniques for sinking shaftsunderwater using robotic construction equipment. There are secant pilesystems, where several small diameter bores are drilled in a ringconfiguration, completed with concrete and then the center of the ringexcavated to create the shaft. There is the caisson sinking method,which formation materials are removed from below the center of caisson,creating a void and causing the casing to sink under its own weight.Soft-ground shafts can be installed with diameters in the range of about3 to about 10 meters.

Drilling Technology

Drilling technology for oil and gas wells is well developed. Drillingtechnologies for soft and hard rock are also well known. Water jetdrilling has been implemented in both oil and gas well drilling,geothermal drilling, waste and groundwater control as well as for hardrock drilling. An example of water jet drilling technology is providedin published papers such as “Coiled Tubing Radials Placed by Water JetDrilling: Field Results, Theory, and Practice” and “Performance ofMultiple Horizontal Well Laterals in Low-to-Medium PermeabilityReservoirs” which are listed as prior art references herein. Prior art“mining for access” methods are based on excavating tunnels,cross-connects and drilling caverns in competent rock above or below thetarget hydrocarbon formation. The competent rock provides ground supportfor the operation and, being relatively impermeable, to some extentprotects the work space from fluid and gas seepages from the nearbyhydrocarbon deposit. This approach cannot be applied when formationpressures are high; when the hydrocarbon reservoir is artificiallypressurized for enhanced recovery operations (“EOR”); when thehydrocarbon formation is heated, for example, by injecting steam; orwhen the ground adjacent to the hydrocarbon reservoir is fractured,soft, unstable, gassy or saturated with ground fluids.

One of the present inventors has developed a hybrid drilling methodusing a modified pipe-jacking process in conjunction with a augurcutting tool and a plasticized drilling mud to install horizontal wellsfrom the bottom of a distant shaft into a river bottom formation. Thistechnique was successfully used to develop a Ranney well with a longhorizontal collector well.

Vertical, inclined and horizontal wells may be installed from thesurface by well-known methods. In many cases surface access isrestricted and installing wells from an underground platform such as thebottom of a shaft or a tunnel may be a more practical and cost-effectiveapproach to installing wells. Machine and methodology developments,particularly in the heavy civil underground construction sector, haveopened up new possibilities for an underground approach for installingwells. Discussing some of these techniques, the present inventors havefiled U.S. provisional patent application Ser. No. 60/685,251, filed May27, 2005 entitled “Method of Collecting Hydrocarbons from Tunnels”, andU.S. Ser. No. 60/753,694, filed Dec. 23, 2005 entitled “Method ofRecovering Bitumen” both of which are incorporated herein by thisreference.

TBM and Microtunneling Technology

Soft-ground tunnels can be driven through water saturated sands andclays or mixed ground environments using large slurry, Earth PressureBalance (“EPB”) or mixed shield systems. This new generation ofsoft-ground tunneling machines can now overcome water-saturated or gassyground conditions and install tunnel liners to provide ground supportand isolation from the ground formation for a variety of undergroundtransportation and infrastructure applications.

Developments in soft-ground tunneling led to the practice ofmicro-tunneling which is a process that uses a remotely controlledmicro-tunnel boring machine combined with a pipe-jacking technique toinstall underground pipelines and small tunnels. Micro-tunneling hasbeen used to install pipe from twelve inches to twelve feet in diameterand therefore, the definition for micro-tunneling does not necessarilyinclude size. The definition has evolved to describe a tunneling processwhere the workforce does not routinely work in the tunnel.

Robotic Excavation Technology

Robotic excavators have been used in a variety of difficult situationssuch as excavating trenches undersea or preforming excavation functionsunderground in unsafe environments. An example of this technology can befound, for example, in U.S. Pat. No. 5,446,980, entitled “AutomaticExcavation Control System and Method”.

Other Means of Forming Underground Drilling Space

The mining and heavy civil underground industries have developed otherprocesses that may be applied to forming drilling rooms for undergroundrecovery of hydrocarbons. These include for example:

1. Hydraulic mining—Hydraulic mining techniques have been successfullydemonstrated in the Alberta oil sands. Proposals have been put forwardwhich involve mining the oil sand by hydraulic means through wells sunkfrom the surface. Such efforts are described, for example, in“Feasibility of Underground Mining of Oil Sand”, Harris and Sobkowicz,1978 and “Feasibility Study for Underground Mining of Oil Sand”, Hardy,1977. Johns in U.S. Pat. No. 4,076,311 issued Feb. 28, 1978 entitled“Hydraulic Mining from Tunnel by Reciprocated Pipes” discloses a methodof hydraulic underground mining of oil sands and other friable mineraldeposits. The present inventors have disclosed a method of hydraulicmining in oil sands in U.S. Provisional Patent Application 60/867,010entitled “Recovery of Bitumen by Hydraulic Excavation” filed Nov. 22,2006. The method of hydraulic mining disclosed includes: several meansof drilling production and tailings injection wells; several means ofaugmenting hydraulic excavation for example by inducing block caving;means of isolating the underground personnel areas from formation gasesand fluids; and means of backfilling the excavated volumes withtailings.2. Horizontal secant pile—Secant pile walls or tunnels may be formed byconstructing a longitudinal assembly of piles which contact each otherto define a tunnel. The volume contained inside the pile assembly isexcavated using the piles as ground support. The piles may befabricated, for example, from steel tubes or reinforced concrete. Thepiles may be installed by pipe-jacking, pile driving, drilling oraugering. Primary piles are installed first with secondary pilesconstructed in between primary piles once the latter gain sufficientstrength. Pile overlap is typically in the order of about 50 to 100 mm.3. Soil Mixing—Various methods of soil mixing (sometimes referred to asjet grouting), mechanical, hydraulic, with and without air, andcombinations of both types have been used widely in Japan for about 20years and more recently have gained wide acceptance in the UnitedStates. The soil mixing, ground modification technique, has been usedfor many diverse applications including building and bridge foundations,retaining structures, liquefaction mitigation, temporary support ofexcavation and water control. Names such as Jet Grouting, Soil Mixing,Cement Deep Mixing (CDM), Soil Mixed Wall (SMW), Geo-Jet, Deep SoilMixing, (DSM), Hydra-Mech, Dry Jet Mixing (DJM), and Lime Columns areknown to many. Each of these methods has the same basic root, findingthe most efficient and economical method to mix cement (or in some casesfly ash or lime) with soil and cause the properties of the soil tobecome more like the properties of a soft rock.4. Ground modification (also known as ground freezing)—Historically,ground modification for civil applications has been used primarily onlarge projects where groundwater and caving soils create an unstablesituation and ground freezing represents the only possible solution.Ground freezing has been used to stabilize excavation walls in cavingsoils and to prevent groundwater seepage into the deep excavations nearexisting structures. The technology has been applied in Europe and NorthAmerica for more than a century on a variety of construction and miningprojects. The freezing method aims to provide artificially frozen soilthat can be used temporarily as a support structure for tunneling ormining applications. It is a versatile technique that increases thestrength of the ground and makes it impervious to water seepage.Excavation can proceed safely inside the frozen ground structure untilconstruction of the final lining provides permanent support. In contrastto grouting works the freezing method is completely reversible and hasno environmental impact. Ground freezing is not limited by adverseground conditions and may be used in any soil formation, regardless ofstructure, grain size, permeability or moderate groundwater flow.5. NATM—New Austrian Tunnelling Method (NATM) As defined by the AustrianSociety of Engineers and Architects, the NATM “ . . . constitutes amethod where the surrounding rock or soil formations of a tunnel areintegrated into an overall ring-like support structure. Thus thesupporting formations will themselves be part of this supportingstructure.” In world-wide practice, however, when shotcrete is proposedfor initial ground support of an open-face tunnel, it is often referredto as NATM. In current practice, for soft-ground tunnels which arereferred to as NATM tunnels, initial ground support in the form ofshotcrete (usually with lattice girders and some form of groundreinforcement) is installed as excavation proceeds, followed byinstallation of a final lining at a later date. Soft ground can bedescribed as any type of ground requiring support as soon as possibleafter excavation in order to maintain stability of the NATM for softground. As long as the ground is properly supported, NATM constructionmethods are appropriate for soft-ground conditions. However, there arecases where soft-ground conditions do not favor an open face with ashort length of uncompleted lining immediately next to it, such as inflowing ground or ground with short stand-up time (i.e., failure todevelop a ground arch). Unless such unstable conditions can be modifiedby dewatering, spiling, grouting, or other methods of groundimprovement, then NATM may be inappropriate. In these cases, close-faceshield tunneling methods may be more appropriate for safe tunnelconstruction.

Key features of the NATM design philosophy are:

-   -   The strength of the ground around a tunnel is deliberately        mobilised to the maximum extent possible.    -   Mobilisation of ground strength is achieved by allowing        controlled deformation of the ground.    -   Initial primary support is installed having load-deformation        characteristics appropriate to the ground conditions, and        installation is timed with respect to ground deformations.    -   Instrumentation is installed to monitor deformations in the        initial support system, as well as to form the basis of varying        the initial support design and the sequence of excavation.    -   Key features of NATM construction methods are:    -   The tunnel is sequentially excavated and supported, and the        excavation sequences can be varied.    -   The initial ground support is provided by shotcrete in        combination with fibre or welded-wire fabric reinforcement,        steel arches (usually lattice girders), and sometimes ground        reinforcement (e.g., soil nails, spiling).    -   The permanent support is usually (but not always) a        cast-in-place concrete lining. It should be noted that many of        the construction methods described above were in widespread use        in the US and elsewhere in soft-ground applications before NATM        was described in the literature.

For underground recovery of hydrocarbons, there remains a need formodified excavation methods and a selection method to utilize shafts asan underground base to install a network of wells either from the shaftitself or drilling rooms, tunnels and the like, initiated from theshaft. There is a need for safe and economical process of installing anetwork of hydrocarbon recovery wells from an underground work spacewhile maintaining isolation between the work space and the groundformation. It is the objective of the present invention to provide amethod and means of selecting the most appropriate process for providingadequate underground workspace by selecting one or more of a number ofmethods for installing, operating and servicing a large number of wellsin various levels of a hydrocarbon deposit which may contain free gas,gas in solution and water zones.

SUMMARY

These and other needs are addressed by embodiments of the presentinvention, which are directed generally to methods for installingunderground workspace in or near a hydrocarbon deposit that is anappropriate workspace from which to drill, operate and/or service wellsapplicable to any of a number of methods of recovering hydrocarbons andselecting an appropriate method for a given application. The presentinvention includes a number of innovative methods for developingworkspace for drilling from a shaft installed above, into, or below ahydrocarbon deposit, particularly when the hydrocarbon reservoir is atsignificant formation pressure or has fluids (water, oil or gases) thatcan seep into or flood a workspace. These methods can also be used fordeveloping workspace for drilling from a tunnel installed above, into,or below a hydrocarbon deposit. The entire process of installing theshafts and tunnels as well as drilling and operating the wells incarried out while maintaining isolation between the work space and theground formation. The present invention also discloses a procedure forevaluating the geology in and around the reservoir and using this andother information to select the most appropriate method of developingworkspace for drilling from a shaft and/or tunnel.

In one embodiment, an excavation method includes the steps:

(a) forming a substantially vertically inclined shaft;

(b) at a selected level of the shaft, forming a plurality of recesscavities extending approximately radially outward from the shaft, theselected level of the shaft being adjacent to or near ahydrocarbon-containing formation; and

(c) drilling one or more wells outward from a face of each of the recesscavities, each of the wells penetrating the hydrocarbon-containingformation.

The recess cavities are preferably manned. More preferably, each of therecess cavities has a diameter ranging from about 1 to about 2 metersand a length ranging from about 4 to about 10 meters.

To protect underground personnel and inhibit underground gas explosions,the recess cavities and at least some of the shaft are lined with aformation-fluid impervious liner.

The shaft normally includes a number of spaced apart levels. Each of thespaced apart levels comprises a plurality of approximately radiallyoutwardly extending recess cavities.

In one configuration, the drilling step (c) includes the further stepsof:

(c1) from the shaft, drilling through a flange positioned adjacent to asurface of the shaft to form a drilled hole extending outwardly from theshaft;

(c2) placing a cylindrical shield in the drilled hole;

(c3) securing the shield to the surface of the shaft; and

(c4) introducing a cementitious material into an end of the drilled holeto form a selected recess cavity.

When the cementitious material sets, the set cementitious material andshield will seal the interior of the cavity from one or more selectedformation fluids.

In one configuration, the drilling step (c) includes the further stepsof:

(c1) from the shaft, drilling, by a drill stem and bit, through a flangeand sealing gasket, the flange and gasket being positioned on a surfaceof the shaft, to form a drilled hole extending into thehydrocarbon-containing formation;

(c2) while the hole is being drilled, extending a cylindrical shieldinto the hole in spatial proximity to the drill bit, the shieldsurrounding the drill stem;

(c3) pumping a cementitious composition through the drill stem and intoa bottom of the drilled hole;

(c4) securing the shield to the flange; and

(c5) after the cementitious composition has set, removing the drill stemfrom the hole to form a selected recess cavity.

When the cementitious material sets, the set cementitious material andshield will seal the interior of the cavity from one or more selectedformation fluids.

In another embodiment, a drilling method includes the steps:

(a) from a manned excavation, drilling through a flange positionedadjacent to a surface of the excavation to form a drilled hole extendingoutwardly from the excavation;

(b) placing a cylindrical shield in the drilled hole;

(c) securing the shield to the surface of the excavation; and

(d) introducing a cementitious material into an end of the drilled holeto form a selected recess cavity.

When the cementitious material sets, the set cementitious material andshield will seal the interior of the hole from one or more selectedformation fluids.

In the drilling step, a drill stem and attached bit drill through aflange and the sealing gasket and into a hydrocarbon-containingformation. The flange and gasket are positioned on a surface of theexcavation. During the drilling step, a cylindrical shield is preferablyextended into the hole in spatial proximity to the drill bit, the shieldsurrounding the drill stem. The shield may or may not rotate in responseto rotation of the bit.

In yet another embodiment, an excavation method includes the steps:

(a) excavating a shaft, the excavated shaft being at least partiallyfilled with a drilling fluid and having a diameter of at least about 3meters; and

(b) an automated and/or remotely controlled excavation machine formingan excavation extending outwards from the shaft, the excavation machinebeing positioned below a level of and in the drilling fluid when formingthe excavation.

The position of the excavation machine is preferably determined relativeto a fixed point of reference in the shaft. The excavation machine istypically immersed in the drilling fluid when forming the excavation,and, to track the machine's position, the excavation machine is normallyconnected to the fixed point of reference. The excavation machine iscontrolled remotely by an operator.

In one configuration, the excavation machine is at least partiallyautomated, and the excavation is located in a hydrocarbon-containingformation.

The method can include the further steps:

(c) removing the excavation machine from the excavation;

(d) filling, at least substantially, the excavation with a cementitiousmaterial that displaces the lighter drilling fluid from the filledportion of the excavation;

(e) repositioning the excavation machine in the shaft at an uppersurface of the cementitious material, after the cementitious materialhas set, with the repositioned excavation machine still being immersedin the drilling fluid;

(f) removing, by the repositioned excavation machine, at least a portionof the set cementitious material to form a lined excavation; and

(g) installing, in the lined excavation and while the lined excavationis filled with the drilling fluid, a permanent liner, the permanentliner being positioned interiorly of the remaining cementitiousmaterial.

In yet another embodiment, an excavation method includes the steps:

(a) drilling a plurality of substantially horizontal drill holes, thedrill holes defining an outline of a volume to be excavated;

(b) filling, at least substantially, the drill holes with a cementitiousmaterial, to inhibit the passage of a selected formation fluid betweenthe adjacent, filled drill holes and/or to provide structural support;and

(c) thereafter excavating the volume to be excavated.

The volume to be excavated is positioned preferentially in ahydrocarbon-containing formation, and each of the drill holes has anormal diameter of at least about 0.33 meters and a length of up toabout 800 meters.

The filling step (b) can include the further steps of: (b1) after aselected hole is drilled and while a drill stem is positioned in theselected hole, pumping the cementitious material through the drill stemand into the hole and

(b2) while the cementitious material is being introduced into theselected hole, removing gradually the drill stem from the selected hole,the rate of removal being related to the rate of introduction of thecementitious material into the selected hole.

In yet another embodiment, a method for recovering a bitumen-containingmaterial is provided that includes the steps:

(a) determining, for a selected in situ hydrocarbon-containing deposit,a set of possible underground and/or surface excavation methods;

(b) determining a set of surface restrictions above and around thedeposit;

(c) determining a set of regulatory requirements applicable toexcavation of the deposit;

(d) determining a set of physical limitations on underground excavationof the deposit;

(e) determining a set of physical limitations on surface excavation ofthe deposit;

(f) determining a set of data for the deposit;

(g) determining a set of geotechnical data for at least one formationother than the deposit;

(h) based on the sets of surface restrictions, regulatory requirements,physical limitations, deposit data, and geotechnical data, assigning arecovery cost to each member of the set of possible excavation methods;

(i) based on a comparison of the recovery costs of the members,selecting a preferred excavation method to be employed;

(j) in response to the preferred excavation method being an undergroundmethod, performing the following substeps:

-   -   (j1) for an inclined access excavation to the deposit, the        inclined access excavation being a shaft and/or decline,        determining whether the inclined access excavation will        intercept a formation with a potentially harmful formation        fluid;    -   (j2) in response to the inclined access excavation intercepting        a formation having at least one potentially harmful formation        fluid, requiring men to be absent from the inclined access        excavation when the access excavation is excavated in the        vicinity of the formation;    -   (j3) selecting a bitumen recovery method to be employed, wherein        possible bitumen recovery methods comprise thermal, gravity        drain, and cold recovery methods; and    -   (j4) based on the selected bitumen recovery method,        selecting (a) a location in the underground excavation for well        head placement, the location being at least one of in the        inclined access excavation, in a recess cavity extending        outwardly from the inclined access excavation, in a drilling        room extending outwardly from the inclined access excavation,        and in a tunnel extending outwardly from the inclined access        excavation and (b) a position of the location relative to the        deposit, the possible positions being above, in, and below the        deposit.

Typically, the deposit data include deposit depth, areal extent, andgeology, and the geotechnical data are for a formation positioned abovethe deposit.

In one configuration, the method includes the further substep:

-   -   (j5) based on the selected bitumen recovery method, determining        a method for forming the location, the possible methods        comprising ground modification, secant pile, robotic excavation        machine, New Austrian Tunneling Method (NATM), soil mixing, and        hydraulic mining.

Preferably, the method is embodied as a computer program recorded, inthe form of processor-executable instructions, on a computer readablemedium.

The maintenance of a sealed work space can provide a safe workingenvironment for accessing, mobilizing and producing hydrocarbons fromunderground. The seals can prevent unacceptably high amounts of unwantedand dangerous gases from collecting in the excavation. It can also allowthe excavation to be located in hydrologically active formations, suchas formations below a body of water or forming part of the water table.

In certain embodiments, the present invention discloses a method forinstalling an underground workspace suitable for drilling wells into ahydrocarbon formation wherein the underground workspace is fully linedin order to provide ground support and isolation from formationpressures, excessive temperatures, fluids and gases. The process ofmaintaining isolation of the underground work space from the formationincludes the phases of (1) installation of underground workspace andwells and (2) all production and maintenance operations from theunderground workspace. Because the underground workspace is installedand operated in full isolation from the formation pressures and fluids,the workspace can be installed above, inside or below the hydrocarbonformation in soft or mixed ground.

The present invention can provide a number of advantages. First, thevarious excavation methods can provide a cost effective, safe way torecover hydrocarbons, particularly bitumen, from hydrocarbon-containingmaterials, even those located beneath otherwise inaccessible obstacles,such as rivers, lakes, swamps, and inhabited areas. The methods canpermit excavation to be performed safely in the hydrocarbon-containingmaterials rather than from a less economical or effective location aboveor below the material. The excavation selection method can permit one toselect the optimal, or near optimal, excavation method for a given setof conditions and restraints. The selection method considers not justthe excavation methods described herein but other known methods thathave proven track records in non-hydrocarbon-containing materials.

The following definitions are used herein:

It is to be noted that the term “a” or “an” entity refers to one or moreof that entity. As such, the terms “a” (or “an”), “one or more” and “atleast one” can be used interchangeably herein. It is also to be notedthat the terms “comprising”, “including”, and “having” can be usedinterchangeably.

The term automatic and variations thereof, as used herein, refers to anyprocess or operation done without material human input when the processor operation is performed. However, a process or operation can beautomatic even if performance of the process or operation uses humaninput, whether material or immaterial, received before performance ofthe process or operation. Human input is deemed to be material if suchinput influences how the process or operation will be performed. Humaninput that consents to the performance of the process or operation isnot deemed to be “material”. The terms determine, calculate and compute,and variations thereof, as used herein, are used interchangeably andinclude any type of methodology, process, mathematical operation ortechnique.

The term module as used herein refers to any known or later developedhardware, software, firmware, artificial intelligence, fuzzy logic, orcombination of hardware and software that is capable of performing thefunctionality associated with that element. Also, while the invention isdescribed in terms of exemplary embodiments, it should be appreciatedthat individual aspects of the invention can be separately claimed.

A cementitious material refers to material that, in one mode, is in theform of a liquid or slurry and, in a different mode, is in the form of asolid. By way of example, cement, concrete, or grout-type cementitiousmaterials are in the form of a flowable slurry, which later dries orsets into cement, concrete, or grout, respectively.

A hydrocarbon is an organic compound that includes primarily, if notexclusively, of the elements hydrogen and carbon. Hydrocarbons generallyfall into two classes, namely aliphatic, or straight chain,hydrocarbons, cyclic, or closed ring, hydrocarbons, and cyclic terpenes.Examples of hydrocarbon-containing materials include any form of naturalgas, oil, coal, and bitumen that can be used as a fuel or upgraded intoa fuel. Hydrocarbons are principally derived from petroleum, coal, tar,and plant sources.

Hydrocarbon production or extraction refers to any activity associatedwith extracting hydrocarbons from a well or other opening. Hydrocarbonproduction normally refers to any activity conducted in or on the wellafter the well is completed. Accordingly, hydrocarbon production orextraction includes not only primary hydrocarbon extraction but alsosecondary and tertiary production techniques, such as injection of gasor liquid for increasing drive pressure, mobilizing the hydrocarbon ortreating by, for example chemicals or hydraulic fracturing the well boreto promote increased flow, well servicing, well logging, and other welland wellbore treatments.

A liner as defined for the present invention is any artificial layer,membrane, or other type of structure installed inside or applied to theinside of an excavation to provide at least one of ground support,isolation from ground fluids (any liquid or gas in the ground), andthermal protection. As used in the present invention, a liner istypically installed to line a shaft or a tunnel, either having acircular or elliptical cross-section. Liners are commonly formed bypre-cast concrete segments and less commonly by pouring or extrudingconcrete into a form in which the concrete can solidify and attain thedesired mechanical strength.

A liner tool is generally any feature in a tunnel or shaft liner thatself-performs or facilitates the performance of work. Examples of suchtools include access ports, injection ports, collection ports,attachment points (such as attachment flanges and attachment rings), andthe like.

A mobilized hydrocarbon is a hydrocarbon that has been made flowable bysome means. For example, some heavy oils and bitumen may be mobilized byheating them or mixing them with a diluent to reduce their viscositiesand allow them to flow under the prevailing drive pressure. Most liquidhydrocarbons may be mobilized by increasing the drive pressure on them,for example by water or gas floods, so that they can overcomeinterfacial and/or surface tensions and begin to flow. Bitumen particlesmay be mobilized by some hydraulic mining techniques using cold water.

A seal is a device or substance used in a joint between two apparatuseswhere the device or substance makes the joint substantially imperviousto or otherwise substantially inhibits, over a selected time period, thepassage through the joint of a target material, e.g., a solid, liquidand/or gas. As used herein, a seal may reduce the in-flow of a liquid orgas over a selected period of time to an amount that can be readilycontrolled or is otherwise deemed acceptable. For example, a sealbetween a TBM shield and a tunnel liner that is being installed, may besealed by brushes that will not allow large water in-flows but may allowwater seepage which can be controlled by pumps. As another example, aseal between sections of a tunnel may be sealed so as to (1) not allowlarge water in-flows but may allow water seepage which can be controlledby pumps and (2) not allow large gas in-flows but may allow small gasleakages which can be controlled by a ventilation system.

A shaft is a long approximately vertical underground opening commonlyhaving a circular cross-section that is large enough for personneland/or large equipment. A shaft typically connects one underground levelwith another underground level or the ground surface.

A tunnel is a long approximately horizontal underground opening having acircular, elliptical or horseshoe-shaped cross-section that is largeenough for personnel and/or vehicles. A tunnel typically connects oneunderground location with another.

An underground workspace as used in the present invention is anyexcavated opening that is effectively sealed from the formation pressureand/or fluids and has a connection to at least one entry point to theground surface.

A well is a long underground opening commonly having a circularcross-section that is typically not large enough for personnel and/orvehicles and is commonly used to collect and transport liquids, gases orslurries from a ground formation to an accessible location and to injectliquids, gases or slurries into a ground formation from an accessiblelocation.

Well drilling is the activity of collaring and drilling a well to adesired length or depth.

Well completion refers to any activity or operation that is used toplace the drilled well in condition for production. Well completion, forexample, includes the activities of open-hole well logging, casing,cementing the casing, cased hole logging, perforating the casing,measuring shut-in pressures and production rates, gas or hydraulicfracturing and other well and well bore treatments and any othercommonly applied techniques to prepare a well for production.

Wellhead control assembly as used in the present invention joins themanned sections of the underground workspace with and isolates themanned sections of the workspace from the well installed in theformation. The wellhead control assembly can perform functionsincluding: allowing well drilling, and well completion operations to becarried out under formation pressure; controlling the flow of fluidsinto or out of the well, including shutting off the flow; effecting arapid shutdown of fluid flows commonly known as blow out prevention; andcontrolling hydrocarbon production operations.

It is to be understood that a reference to oil herein is intended toinclude low API hydrocarbons such as bitumen (API less than ˜10) andheavy crude oils (API from ˜10 to ˜20) as well as higher APIhydrocarbons such as medium crude oils (API from ˜20 to ˜35) and lightcrude oils (API higher than ˜35).

Primary production or recovery is the first stage of hydrocarbonproduction, in which natural reservoir energy, such as gasdrive,waterdrive or gravity drainage, displaces hydrocarbons from thereservoir, into the wellbore and up to surface. Production using anartificial lift system, such as a rod pump, an electrical submersiblepump or a gas-lift installation is considered primary recovery.Secondary production or recovery methods frequently involve anartificial-lift system and/or reservoir injection for pressuremaintenance. The purpose of secondary recovery is to maintain reservoirpressure and to displace hydrocarbons toward the wellbore. Tertiaryproduction or recovery is the third stage of hydrocarbon productionduring which sophisticated techniques that alter the original propertiesof the oil are used. Enhanced oil recovery can begin after a secondaryrecovery process or at any time during the productive life of an oilreservoir. Its purpose is not only to restore formation pressure, butalso to improve oil displacement or fluid flow in the reservoir. Thethree major types of enhanced oil recovery operations are chemicalflooding, miscible displacement and thermal recovery.

Soft ground means any type of ground requiring substantial support assoon as possible after the excavated opening is formed ion in order tomaintain stability of the opening. Soft-ground is generally easy toexcavate by various mechanical or hydraulic means but requires some formof ground support to maintain the excavated opening from collapse.Ground support may include, for example, permanent solutions such asgrouting, shotcreting, or installation of a concrete or metal liner; ortemporary solutions such as freezing or soil modification.

A drilling room as used herein is any self-supporting space that can beused to drill one or more wells through its floor, walls or ceiling. Thedrilling room is typically sealed from formation pressures and fluids.

Hydraulic mining means any method of excavating a valuable ore by impactand/or erosion of high pressure water from a hose or water jet nozzle.

Secant Pile means an opening formed by installing intersecting concretepiles by either drilling, augering, jacking or driving the piles intoplace and then excavating the material from the interior of the openingformed by the piles. A secant pile (sometimes called the tangent) may beformed using primary piles installed first and then secondary pilesinstalled in between or overlapping the primary piles, once the primarypiles attain sufficient strength.

Ground modification typically means freezing the ground to stabilize anexcavation in soft ground especially caving soils and to preventgroundwater seepage into the excavation. The freezing method providesartificially frozen soil that can be used temporarily as a supportstructure for tunneling or mining applications. The process increasesthe strength of the ground and makes it impervious to water seepage sothat excavation can proceed safely inside the frozen ground structureuntil construction of the final lining provides permanent support.

NATM means “New Austrian Tunneling Method” and is generally a methodwhere the surrounding rock or soil formations of a tunnel are integratedinto an overall ringlike support structure and where the supportingformations will themselves be part of this supporting structure.

Soil mixing means any of various methods of soil mixing or jet groutingmethods based on mechanical, hydraulic devices used with or without air,and combinations of each. Soil mixing typically involves methods ofmixing, for example, cement, fly ash or lime with the in-situ soil so asto cause the properties of the soil to become more like the propertiesof a soft rock.

As used herein, “at least one”, “one or more”, and “and/or” areopen-ended expressions that are both conjunctive and disjunctive inoperation. For example, each of the expressions “at least one of A, Band C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “oneor more of A, B, or C” and “A, B, and/or C” means A alone, B alone, Calone, A and B together, A and C together, B and C together, or A, B andC together.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an example shaft, drilling room andtunnel facility.

FIG. 2 is a plan view of a lined shaft and a plurality of well-headrecesses.

FIG. 3 is a cutaway side view of a lined shaft and a offset well-headrecesses.

FIG. 4 is a cutaway side view of a multi-level shaft with a plurality ofwell-head recesses.

FIG. 5 is a close up cutaway side view of a well-head recess withwell-head equipment installed.

FIG. 6 is a cutaway side view of a well-head recess with well-headequipment installed and drilling equipment drilling a well.

FIGS. 7 a-h is a sequence illustrating installing a recess underpressure.

FIG. 8 is a plan view showing a well drilled from a shaft of the presentinvention with offshoots.

FIG. 9 shows plan views of example well patterns drilled from a shaft.

FIG. 10 is an example of a robotic excavator which is prior art.

FIG. 11 is an example of a room excavated at the bottom of a shaft usinga robotic excavator.

FIG. 12 is an example of a finished room excavated at the bottom of ashaft based on the method of the present invention.

FIG. 13 is an example of a multiple rooms excavated at different levelsof a shaft.

FIG. 14 is a sequence of principal operations to drill a shaft and roomunder formation pressure.

FIG. 15 shows a prior art shaft lining method in more detail.

FIG. 16 is an isometric view of a drilling room formed by the secantpile method.

FIG. 17 is a schematic illustrating a sequence of forming a concretepile in a formation.

FIG. 18 is a flow diagram for selecting surface or underground recoveryof hydrocarbons.

FIG. 19 is a flow diagram for obtaining data for design of the accessmethod for an underground recovery operation.

FIG. 20 is a flow diagram designing the selected method of access forunderground recovery of hydrocarbons.

FIG. 21 is a flow diagram for selecting a location for drillinglocations for underground recovery of hydrocarbons.

FIG. 22 is a flow diagram for selecting a workspace location fordrilling for underground recovery of hydrocarbons.

FIG. 23 is a flow diagram for selecting a workspace method for drillingfrom a shaft for underground recovery of hydrocarbons.

FIG. 24 is a flow diagram for selecting a workspace method for drillingfrom a decline for underground recovery of hydrocarbons.

FIG. 25 is a schematic representation of a computerized process forimplementing the example decision process shown in FIGS. 18 through 24.

FIGS. 26 a-c illustrate a sequence illustrating installing a recess bypipe-jacking. The method is applicable when a recess is to be installedform inside a lined shaft into the surrounding formation when thesurrounding formation has or is thought to have a formation pressureand/or the possibility of substantial water or gas inflow. The groundformation in which the recess is sunk is on the side 2602. FIG. 26 ashows the shaft wall 2601 with a drill assembly in position to begindrilling. The drill assembly is comprised of a drill bit 2606 and adrill steel 2608, both of which are contained in a steel shield 2607.The steel shield 2607 forms a pressure vessel around the drill assemblyduring the drilling phase of the operation. The steel shield 2607 issealed to the drilling rig (not shown) by any number of well-known means(also not shown). The steel shield 2607 will ultimately form the housingof the recess that is being installed. The steel shield 2607 may berotated during drilling or it may be pipe-jacked (pushed but notrotated). FIG. 26 b shows the drill bit 2606 and steel shield 2607having drilled through the shaft liner wall 2601 and continuing to drillor bore into the formation. FIG. 26 c shows the drill bit 2606 and steelshield 2607 penetrated into the formation.

FIG. 27 shows a schematic side view of wellhead control equipmentinstalled in a tunnel or shaft liner.

FIG. 28 illustrates features of tunnel liner sealing.

DETAILED DESCRIPTION

FIG. 1 is an isometric view of an example shaft, drilling room andtunnel facility. As an example, a shaft 104 is shown installed throughan overburden 101, a hydrocarbon reservoir zone 102 and terminating in abasement layer 103. Wells may be drilled into the hydrocarbon formation102 from the shaft 102 as will be described in subsequent figures. Adrilling room 105 is shown installed in the hydrocarbon formation 102from the shaft 104 and wells 107 are shown installed into thehydrocarbon formation 102 from the drilling room 105. As can beappreciated, the drilling room can be installed from the shaft 104above, within or below the hydrocarbon formation 102, depending on, forexample, the type of reservoir being produced. A tunnel 105 is alsoshown installed in the hydrocarbon formation 102 from the shaft 104 andwells 107 are shown installed into the hydrocarbon formation 102 fromthe tunnel 105. In effect the tunnel can be considered as a longdrilling room but is typically formed by a tunnel boring machine orother tunneling technique. As will be discussed in subsequent figures, adrilling room may be formed by a variety of methods but are generallytoo short to warrant excavation by a tunneling machine. As can beappreciated, drilling rooms may be installed in the hydrocarbonformation 102 from the tunnel 106 and wells subsequently installed intothe hydrocarbon formation 102 from these drilling rooms.

Key features of this installation are the junctions 109 between theshaft 104 and the tunnel 106. If these junctions are in a pressurized orgassy or fluid-saturated portion of the formation, they must be sealedjunctions. The junctions are not necessarily sealed during installationas dewatering, degassing or other well known techniques can be appliedduring installation to cope with fluid or gas inflows. A method formaintaining a seal at such junctions 109 during installation isdescribed in FIG. 28.

Recesses Formed in Shaft or Tunnel Walls

FIG. 2 is a plan view of a lined shaft 201 and a plurality of well-headrecesses 202. The shaft 201 is shown with an inside diameter 203 whichis the range of about 4 meters to about 10 meters. FIG. 2 shows twelverecess cavities 202 which are installed approximately along radial linesfrom the center of the shaft and spaced at approximately equal angles.The diameters 204 of the recesses 202 are in the range of about 1 meterto about 2 meters. The lengths 205 of the recesses 202 are in the rangeof about 4 meters to about 10 meters. Once installed, the recesses 202serve as the working space for installing blow-out preventer and otherwell-head equipment. The recesses are large enough to allow personnel towork in them or to utilize robotic equipment to perform the necessarywork. In this way, a large number of horizontal wells can be drilled outinto the formation from the confined working space at the bottom of theshaft 201. The working volume provided by the recesses can approximatelydouble or triple the working space available on a working level of theshaft alone.

FIG. 3 is a cutaway side view of a lined shaft 301 and a offsetwell-head recesses 305. As can be appreciated, the depth of the shaft307 is determined by the depth of the hydrocarbon deposit beingdeveloped. Typically, the depth of the shaft 307 is in the range ofabout 40 meters to about 500 meters. The shaft liner 301 which istypically formed from concrete has a diameter 302 typically in the rangeof about 3 meters to about 10 meters and a wall thickness 303 that istypically in the range of about 0.1 meter to about 0.4 meters. Thisfigure illustrates how some recesses 305 can be installed on one levelwhile other recesses 306 can be installed on a different level. Thelevels may be separated by a distance 308 which can be as large asdesired but no less than about 1 diameter where the diameter is that ofthe recess. By offsetting recesses, more recesses can be installed inone location. As can be appreciated, wells can be drilled from theoffset recesses into the formation and, using well-known directionaldrilling techniques, can be installed at the same level in thehydrocarbon formation, even though they originate higher or lower in theshaft than some of their neighboring recesses.

FIG. 4 is a cutaway side view of a multi-level shaft with a plurality ofwell-head recesses. This figure illustrates how a single shaft can beused to drill wells into different producing zones within a hydrocarbonreservoir. A lined shaft 401 is shown piercing producing zones 403 and405 and being terminated in producing zone 407. A floor 411 is installedin the shaft to act as a working platform for installing recesses 402which are installed into producing zone 403. As can be appreciated, thefloors can be installed on various levels within the shaft eithersequentially as the shaft is drilled/sunk or they can be added later asneeded to access the various reservoir producing zones. Becausereservoir horizons may be exploited by different techniques (cold flooddrive, gravity drain, thermal stimulation, for example), the variousworking levels within the shaft may be installed or removed when aparticular reservoir zone is produced. As described in FIGS. 2 and 3,anywhere from 1 or 2 to approximately 24 recesses can be installed fromany one level. A second floor 412 is installed in the shaft to act as aworking platform for installing recesses 404 which are installed intoproducing zone 405. The bottom of the shaft 413 acts as a workingplatform for installing recesses 406 which are installed into the bottomproducing zone 407. As can be appreciated, this approach can be used toinstall recesses and, from the recesses, drill wells into as manyproducing zones as are found in the reservoir.

FIG. 5 is a close up cutaway side view of a well-head recess 502 withwell-head equipment 503 installed. The recess 502 is attached and sealedto the shaft liner 501. A method of installing recesses under pressureis fully described in FIG. 8. FIG. 8 also shows a recess end flangewhich has a threaded plug that can be removed for installing thewell-head equipment 503. The well-head equipment 503 is secured to therecess end plate 507 by a flange 504. A portion of the well-headequipment 503 is set into the formation 505. As shown, that portion istypical of well-production operations and collects hydrocarbons anddelivers them to a piping system 506.

FIG. 6 is a cutaway side view of a well-head recess 602 with well-headequipment 603 installed. Also shown is drilling equipment 606 drilling awell 607 through blow-out preventer apparatus 605 located in recess 604.Both recesses shown are located at the bottom of shaft 601. As can beseen, the well-head equipment, once installed as shown by 603, does notinterfere with on-going drilling operations in other recesses. Thismeans, for example, that not all wells need be drilled at the same time.With the recess configuration, additional recesses can be installed andadditional wells can be completed while the original wells continue tobe operated.

A drill rig suitable for drilling from a shaft or tunnel is prior art.As can be appreciated, the drill rig must be compact. As can be seen inFIG. 6, the drill motor is located in the center of the rig andsurrounded by 4 large hydraulic cylinders. This system has a short butpowerful drilling stroke. The length of the wells that can be drilledwith such a rig is in the range of about 100 meters to about 1,000meters. The length is achieved by adding many short lengths of drillsteel as the well is drilled. A drill rig such as shown can be used toinstall casing and service operating wells from time to time. Theprincipal components of the drill rig are a drill motor, a drill steel,hydraulic cylinders. The rig is typically mounted on a skid or it mayhave wheels for moving along a tunnel floor or tracks.

FIGS. 7 a-h illustrates a method of installing a well-head recess whenthere is significant formation pressure. The method is applicable toformation pressures as high as about 20 bars above the ambient pressureinside the shaft. The method is applicable when a recess is to beinstalled from inside a lined shaft into the surrounding formation whenthe surrounding formation has or is thought to have a formation pressureand/or the possibility of substantial water or gas inflow. FIG. 7 ashows a cross-section of shaft liner 701 which is typically formed fromconcrete and has a wall thickness in the range of about 0.1 meter toabout 0.4 meters. The ground formation in which the shaft is sunk is onthe side 702 and the interior, working space of the shaft is on side703. A flange 704 is bolted onto the inside of the shaft liner wall 701and secures a gasket 705 between the flange 704 and the liner wall 701.The flange 704 is typically made of steel and is typically in thethickness range of about 0.1 meter to about 0.4 meters and in thediameter range of about 1 meter to about 2.5 meters. The gasket 705 isabout the same outside diameter as the flange and has an inside diametersubstantially less than the anticipated diameter of the recess to beinstalled. The gasket may be a full-face gasket. The gasket has athickness in the range of about 10 millimeters to about 50 millimeters.The gasket is made from any sealing material such as for example rubber,urethane, polyethylene, teflon or the like. The gasket may be made fromother materials or may be made as a labyrinth of metallic strands orother well-known structure capable of forming a seal. FIG. 7 b shows theshaft wall 701 with a drill assembly in position to begin drillingthrough the gasket 705 and shaft liner 701. The drill assembly iscomprised of a drill bit 706 and a drill steel 708, both of which arecontained in a steel shield 707. The steel shield 707 forms a pressurevessel around the drill rig assembly during the drilling phase of theoperation. The steel shield 707 is sealed to the drilling rig (notshown) by any number of well-known means (also not shown). The steelshield 707 will ultimately form the housing of the recess that is beinginstalled. The steel shield 707 may be rotated during drilling or it maybe pipe-jacked (pushed but not rotated). The diameter of the steelshield 707 is in the range of about 1 meter to about 2 meters and fitsclosely within the inner diameter of the flange 704. The steel shield707 is typically in the thickness range of about 15 millimeters to about50 millimeters. As shown in FIG. 7 b, the drill bit is in position topierce through the sealing gasket 705. FIG. 7 c shows the drill bit 706and steel shield 707 having drilled through the gasket 705 and shaftliner wall 701 and continuing to drill or bore into the formation.Drilling mud is shown being pumped down the center of the drill steel708, as shown by an arrow, and it emerges through jets in the drill bit706. The cuttings and drilling mud flow back through the flutes of thedrill bit 706 and along the annulus formed by the drill steel 708 andthe steel shield 707, as shown by arrows. The gasket 704 forms a sealbetween the outer wall of the steel shield 707 and the inside of theshaft liner wall 701 as shown by 709. FIG. 7 d shows the drill bit 706and steel shield 707 at their maximum penetration into the formation asindicated by length 730. Maximum penetration length 730 is typically inthe range of about 4 meters to about 10 meters beyond the shaft wall701.

FIG. 7 e shows how the drill bit 706 is now withdrawn a small distanceinside the steel shield 707 leaving an excavated void 711. The steelshield 707 is not allowed to move any significant amount. The withdrawaldistance is in the range of about 0.3 steel shield diameters to about 1steel shield diameter. FIG. 7 f shows grout or concrete being pumpeddown a hole 721 in the drill steel 708, as shown by an arrow, andthrough the drill bit 706 to fill the volume 711 with a concrete orgrout plug 712. The plug 712 forms a temporary seal between theformation and the steel shield 707. In FIG. 7 g, the grout or concreteforming the plug 712 has set and has achieved sufficient strength toform a seal and allow the drill bit 706 to be withdrawn back into theshaft. At this time, the seal between drilling rig and the steel shieldmay be broken. FIG. 7 h shows the completed recess. The steel shield 707is secured to the wall flange (flange 704 in FIG. 7 a) by a threaded orwelded flange 715 attached to the end of the steel shield 707. Thegasket 709 (gasket 705 in FIG. 7 a) forms a seal between the shaft wall701, the shaft liner wall 701 and the formation. Another gasket (notshown) may be placed between the flange 715 and the wall flange (flange704 in FIG. 7 a). A steel end plate 716 is installed inside the steelshield 707 and threaded or welded in place, up against the concrete plug712. The steel plate 716 contains a threaded steel plug 717 which may beremoved to install a blow-out preventer apparatus (see FIG. 5). Once theblow-out preventer apparatus is installed, a well drilling rig may bepositioned to drill through the blow-out preventer apparatus and throughthe concrete or grout plug 712 and into the formation.

The drill bit shown in FIG. 7 may comprise a pilot probe that leaves asmaller diameter short hole in the grout or concrete plug. This wouldallow well-head equipment to be installed in the steel end plate inplace of the threaded steel plug. Alternately, the steel plug can beremoved to allow a short hole to be drilled into the grout or concreteplug and then the well-head equipment can be installed. Both methodsallow the well-head equipment to be installed without being exposed toformation pressure.

The sequence of operations shown in FIG. 7 illustrates one embodiment ofthe present invention. The same installation procedure can beaccomplished, for example, using a modified micro-tunneling machinewhich has been suitably modified to allow the cutting head to be removedat the end of the excavation cycle. In the presence of formation fluidsand formation pressure, the recesses may also be formed by other knownmethods. For example, the ground around the proposed recess can befrozen so that the frozen ground will provide temporary ground supportfor a recess hole to be drilled, lined and sealed. If the formationfluids and formation pressures are not substantial, soil mixing isanother procedure that may be used to provide temporary ground supportfor a recess hole to be drilled, lined and sealed. Alternately, a steelpipe can be pipe-jacked or pile driven into the formation to form theliner for a recess. The material within the recess pipe can then beexcavated and an end plate installed to provide a sealed recess.

Drilling Patterns

FIG. 8 is a plan view showing a well 803 being drilled from a recess 802located in a shaft 801. Once the main well 803 is completed, the drillercan drill any number of offshoot wells such as 804 and 805 by well-knowndirectional drilling methods. As shown in FIG. 8, the offshoot wells 804and 805 are directionally drilled to ultimately follow radial pathswhere the radials emanate from the center of the shaft diameter. Thus,although there are a limited number of recesses that can be installed ina shaft of a given diameter, any number of wells can be drilled from theshaft to form a dense radial network of installed wells. As can beappreciated, the offshoot wells can be drilled to follow any trajectoryand do not have to form a radial network as shown.

FIG. 9 a is a plan view of a circular well pattern drilled from a shaft.Wells such as 901 may be drilled out approximately radially as shown todrain a circular area of reservoir. Many wells may be drilled from alimited number of recesses as described in FIG. 8. For example, if thewells are approximately 700 meters long, the pattern shown in FIG. 9 awould be capable of draining approximately 375 acres of reservoir. Ascan be appreciated, additional wells can be drilled from other levelswithin the shaft such as shown for example in FIG. 4. FIG. 9 b is a planview of an elliptical well pattern drilled from a shaft. Wells such as902 may be drilled out approximately radially with variable lengths asshown, to drain an elliptical area of reservoir. For example, if theshortest wells are 400 meters long and the longest wells are 1,000meters in length, then the area drained is approximately 310 acres ofreservoir. FIG. 9 c is a plan view of a well pattern drilled from ashaft into a long narrow hydrocarbon deposit. In this example, a shaftis sunk at one end of the reservoir and a number of wells 903 aredirectionally drilled from a few recesses on one side of the shaft,primarily in one direction as shown Such a patter might be employed, forexample, to drain a reservoir that is located under a river or areservoir that follows, for example, an ancient river bed.

Robotic Excavators

Shaft costs are diameter dependent so deep, large diameter shafts(shafts with diameters in the range of about 10 to 35 meters) can bevery costly. A shaft for oil recovery needs a large diameter workspacenear or at the bottom to accommodate drilling and well-head equipment.As described above, one method of providing space for drilling andwell-head equipment is to install recesses such as described above.Another method is to enlarge the bottom of a shaft as described insubsequent figures. As with the previous method, these installations arenot straightforward when in the presence of formation pressures andfluids. Robotic excavators have been used for a variety of excavationoperations under water, including deep-sea operations. Roboticexcavators can be used to enlarge the bottom of a shaft in acost-effective and safe manner.

FIG. 10 is an example of a robotic excavator which is prior art. Thisfigure shows a road-header type cutting head 1001 that cuts by rotatingat the end of a hydraulically extendable arm 1002. The angle of the armis controlled by hydraulic cylinders 1003. The excavating machine canrotate about its base using a mechanical rotary table 1005 and can moveback and forth using hydraulic cylinders 1004. As can be appreciated,all of these mechanical and hydraulic subsystems can be operatedremotely using various means such as a communications bundle andon-board camera systems to allow an operator to remotely control anexcavation process with such a machine.

FIG. 11 is an example of a room 1103 formed by concrete and excavated atthe bottom of an unlined shaft using a robotic excavator 1104. Theunlined shaft is in soft ground 1102 and is kept open by drilling fluid1101. The process by which the shaft and room are formed is described inmore detail in FIG. 14.

FIG. 12 is an example of a finished room 1202 excavated at the bottom ofa lined shaft 1201 based on the present invention. The interior 1203 ofthe shaft 1201 and room 1202 is filled with air in preparation forworkers to begin well drilling operations from the room 1202. The pin1204 is left over from the construction of the room 1202 and was used asa reference marker for the robotic excavator described in FIGS. 11 and12. The process by which the lined shaft 1201 and lined room 1202 areformed is described in more detail in FIG. 21. The shaft 1201 envisionedin this embodiment has a diameter in the approximate range of 3 to 5meters. The room 1202 is envisioned to have a diameter in the range ofabout 10 to 35 meters.

FIG. 13 is an example of a multiple rooms excavated at different levelsof a shaft using the same methods as described above. This figure showsa lined shaft 1301 with an upper lined room 1302; and a continuation ofa lined shaft 1303 terminating in a bottom lined room 1304. Onceoutfitted with utilities working platforms, elevators, ventilation ductset cetera, such a room/shaft configuration could be used, for example,to drill wells into different horizons of a hydrocarbon formation. Ascan be appreciated, more than 2 rooms can be excavated. As can furtherbe appreciated, this method of forming rooms allows most of the shaft tobe drilled or sunk with a small, less costly diameter, in theapproximate diameter range of 3 to 5 meters, and still provide roomwhere the other work, such as for example, drilling can be carried out.This is a less costly approach than drilling a large diameter shaftwhere the diameter may be in the range of about 12 to 35 meters, whichis the approximate diameter range of drilling rooms required forinstalling multiple wells. As can be further appreciated, a non-roboticshaft drilling machine can be used in the finished upper room to drillthe lower section of shaft as long as the column of drilling mud , nowonly up to the upper room floor level, is sufficient for ground supportof the lower unlined section of shaft.

FIG. 14 is a sequence of principal operations to drill a lined shaft andlined room under formation pressure. In this example, the ground throughwhich the shaft is drilled and the room is excavated is assumed to besoft ground. That is the walls of excavations are not self supportingsuch as they would be , for example, in hard rock. Therefore the wallsof the shaft and room must be supported at all times during excavationuntil the walls can be finished and lined, typically with concrete forlasting ground support. This is particularly important in soft-groundwhere there may be gas and/or water zones and the potential for largefluid in-flows.

FIG. 14 a shows a shaft 1401 being drilled by a large rotary bit 1403.Drilling mud 1404 is forced down the center of drill rod 1402 andre-circulates up the annulus between the drill rod 1402 and the openshaft wall 1401 as indicated by the flow arrows. This procedure iswell-known and used to drill soft-ground shafts in the approximately 3to 5 meter diameter range.

FIG. 14 b shows the shaft 1405 at its maximum depth. FIG. 14 c shows theunlined shaft 1406 with the drill assembly withdrawn. The shaft wallsare held in place by the pressure of the column of drilling mud 1407.Also shown is a reference pin or marker 1409 at the bottom 1408 of theshaft 1406.

FIG. 14 d shows a robotic excavator 1415 which has been positioned atthe bottom of an open shaft 1411. The excavator 1415 is excavating aroom 1413 at the bottom of shaft 1411 while immersed in drilling mud1412 whose pressure is providing stability for the walls of both theshaft 1411 and room 1413. The excavator 1415 is attached to referencepin 1414 at the bottom of the shaft to provide a known reference pointfor the remotely located operator to guide the progress of the roomexcavation. As can be appreciated, it may require more than oneexcavator to complete the room excavation. For example, a small roboticexcavator may be used to form an excavation slightly larger in diameterthan the shaft so that a large robotic excavator can continue to enlargethe room. Excavation cuttings are carried away by circulating mud.

FIG. 14 e shows the finished but unlined room 1413 and the unlined shaft1411 where both are stabilized by the column of drilling fluid 1412.Reference pin or marker 1414 is also shown at the bottom of the shaft.

FIG. 14 f shows a drilling bit 1419 lowered to the top entrance to theexcavated room. A weak mix of concrete (for example a 2 sack mix) isinjected down the center conduit of the drill rod and drill bit anddisplaces the drilling fluid 1420 back up the annulus between the drillrod and the shaft walls and replaces the drilling fluid 1420 in the roomwith weak concrete 1421. As can be appreciated, another speciallydesigned apparatus can be used to inject the concrete and displace thedrilling fluid.

FIG. 14 g shows the drilling apparatus or other specially designedapparatus withdrawn, leaving the room 1422 full of weak concrete 1421while the shaft 1411 remains open with its walls supported by thepressure of mud column 1423. A second reference pin or marker may beinstalled in the top portion of the concrete as shown.

FIG. 14 h shows a robotic excavator 1427 now excavating a room in theconcrete 1423. The open or unlined shaft 1411 and the excavated portionof the concrete continue to be filled with drilling mud 1422 forsupport. The excavator is attached to reference pin or marker at thebottom of the shaft so that it can excavate within the concrete andleave walls of a desired sufficient thickness to provide ground supportwhen the drilling fluid is removed.

FIG. 14 i shows the room excavation completed with concrete walls 1425.Unlined shaft 1411 continues to be filled with drilling mud 1422 forsupport.

FIG. 14 j shows a concrete liner 1423 being installed in the shaft. Theliner is installed by any of several well known methods. As shown inFIG. 14 j, for example, a slip form lining rig is utilized to pourcast-in-place concrete from the surface to the bottom of the shaft, onesection at a time. The drilling mud 1426 in the shaft is removed alittle at a time during the lining operation and replaced by air 1428for the shaft liner installation workers.

FIG. 14 k shows the process of lining the shaft completed so that alined shaft 1430 is not connected and sealed to a lined room 1431. Theinterior 1432 of the shaft and room can now be purged of all drillingmud and filled with air. The system is now ready for installation of theremaining shaft utilities and equipment and the room is ready forwell-drilling operations to begin.

FIGS. 14 a through 14 k illustrate a method of forming a room at thebottom of a shaft in soft-ground. As can be appreciated, any number ofrooms of any of a number of shapes can be formed in this way. It is alsopossible to form the shaft liner by displacing the drilling mud in theshaft with a weak concrete and re-drilling the shaft into the concretecolumn, leaving concrete shaft walls of a desired thickness.

FIG. 15 shows a prior art shaft lining method in more detail. FIG. 15 ashows shaft liner sections 1501, 1502 and 1503 installed. Below theliner sections, the unlined portion of the shaft remains filled withdrilling mud 1505 for support of the unlined shaft walls. The linedsection of the shaft can be filled with air 1504. FIG. 15 b shows thecompleted shaft now lined down to the lined room at the bottom. Theshaft liner sections 1501, 1502, 1503 and the connecting liner section1504 are shown. The entire interior of the shaft and room can be filledwith air 1506 and is now ready for equipping the shaft and room andmoving into well drilling operations (or whatever other operations orequipment operation the room is to be used for).

Horizontal Secant Pile Method

FIG. 16 is an isometric view of a drilling room 1604 having a height1603 and length 1605 formed by the secant pile method (sometimes calledthe tangent pile method). The secant pile method is expected to reliablyinstall guided borings 1602 in, for example, oil sands 1601 to diametersof at least about 0.33 meters and lengths up to about 800 m. To supporttunnel construction, similar bores could reliably be increased todiameters of about ½ to 1½ meters and then be filled with concrete.Groups of these horizontal concrete-filled bores could be used to createtemporary support for construction of tunnel floors, walls and ceilingarches. A method for installing concrete piles with the accuracyrequired to form a secant pile structure such as shown in FIG. 16 usingdrilling techniques is described in FIG. 17. The pile can be formed frommaterial such as concrete, with the strength of the concrete dictated bythe strength requirements of the drilling room 1601 walls. For examplethe piles can be formed from lean concrete to full strength concrete.When thermal recovery operations are planned, the concrete can be madewith the required thermal properties to maintain strength at elevatedtemperatures (typically in the range of about 200 C to about 300 C inthermal recovery operations).

Compared to jet grouting or other soil mixing techniques, this approachwould anticipate the following advantages:

-   -   Uniform mechanical characteristics (e.g., compressive and        tensile strength, permeability, heat transfer, susceptibility to        thermal degradation) over the entire length of the        concrete-filled bore.    -   Superior material strength when required.    -   Able to precisely project as far as the currently anticipated        incremental tunnel drives of about 250 m (and probably to about        800 meters or more if needed).    -   Favorable cost characteristics.

FIG. 17 is a schematic illustrating a sequence of forming a concretepile in a formation. This figure represents operations for implementingan innovative means of forming a concrete pile in, for example, an oilsand formation which has gases dissolved in the bitumen component of theoil sands. As shown in FIG. 17 a, a well 1703 is drilled into the oilsand 1701 from the main access tunnel (not shown) by conventional meanssuch as a rotary drill using circulated mud to lubricate the bit 1702and support the hole 1703. Either forward circulation as shown orreverse circulation drilling techniques can be used. In forward orconventional circulation, drilling mud is pumped down a conduit 1704 inthe drill rod 1705 and returns via the annulus 1706 formed by the drillrod 1705 and the well bore 1703. FIG. 17 b shows the drill bit 1702 atthe end of drilling into the oil sand deposit 1701. FIG. 17 c shows thedrill bit 1702 being withdrawn down drill hole 1708 and a low strengthconcrete being pumped into the hole 1708 via the drill rod conduit 1709.As shown by FIG. 17 d, when the drill bit is fully withdrawn, the hole1708 is filled with low strength concrete. The diameter of the open hole1708 is in the range of about 0.5 meters to about 2 meters. Thecompressive strength of the concrete is in the range of 500 to 1,000psi.

Method of Selecting Underground Drilling Workspace Method

There are many conventional and unconventional hydrocarbon reservoirsthat have yet to be exploited because of surface restrictions or becauseof the economics of recovery. For example, a reservoir may lay under,for example, a large lake, a town, a national park or a protectedwildlife habitat. If the reservoir can be accessed from underground, itis possible to remove most of the surface footprint of a recoveryoperation to an underground workspace and therefore bypass most if notall the surface restrictions. Some reservoirs may require a densenetwork of wells to achieve an economically viable recovery factor. Itmay be less expensive to develop underground drilling workspace where alarge number of short wells can be installed rapidly rather than todrill all the wells from the surface through unproductive overburden toreach the reservoir.

There are many factors that go into determining whether a recoveryoperation should be carried out from the surface or from underground.There are even more factors that go into determining how a recoveryoperation should be carried out once underground access is achieved. Thefollowing decision processes illustrate a method of making these complexdecisions based on first on initial delineation of the reservoir tosubsequent adaptation to foreseen or unforseen conditions onceunderground access to the reservoir is achieved. The following decisionprocess is one of many that can be taken and is illustrative primarilyof a decision process that might apply to an underground reconveyoperation.

FIG. 18 is a flow diagram for selecting surface or underground recoveryof hydrocarbons. The design of a hydrocarbon recovery operation 1801 isinitiated with an estimate of the economic viability 1802 of the targethydrocarbon reservoir. This includes, for example, some knowledge of thereservoir size, barrels of hydrocarbon in place, quality of thehydrocarbon, availability of infrastructure, potential difficulties inrecovery and of course, the expected price of oil over the duration ofthe recovery operation. This preliminary analysis 1802 leads to apreferred method of recovery 1804 which can be pumping usingconventional well recovery methods, gravity drain in certain permeablereservoirs with high API oil or thermal methods, typically using steamor diluent to mobilize a heavy oil or bitumen. In addition, thepossibility of secondary and other tertiary recovery methods may beconsidered in step 1803. In step 1804, the various surface restrictionsabove and around the reservoir are considered. These include, forexample, access limited by weather, ownership of hydrocarbon rights orrestrictive surface rights by others, restriction due to various animalmating seasons, towns, lakes, parks and other existing impediments todrilling operations. If restrictions determined in step 1804 eliminate asurface operation 1805, the feasibility of an underground operation maybe considered in step 1806 and its economic feasibility estimated 1807.If both surface and underground recovery are possible, the variousfactors including cost are weighed and a decision is made in step 1808to go with either (S) a surface operation which would follow steps 1809and 1810 and be carried out in any of many well-known surface-baseddrilling and recovery projects; or by an underground recovery operation(U). If the decision is made to go with an underground recoveryoperation (U), then a preliminary design is initiated 1811 in which theproblems associated with developing underground access are estimated1812 and the economic viability of the various approaches is confirmed1813. Once the decision has been made to go with an underground recoveryoperation, a more detailed design process is initiated 1814.

FIG. 19 is a flow diagram for obtaining more precise data 1901 forselection of an underground access method for a recovery operations ofhydrocarbons. This involves a determination of reservoir depth,thickness, number of pay zones, geology of the pay zones and zonesbetween, above and below the pay zones in step 1902. The geologyincludes estimates of porosity, permeability, oil-water ratio and thelike. This data leads to an estimate of barrels-of-oil-in-place 1903. Anext step 1904 is to revisit the preliminary analysis described in FIG.18 and confirm the preferred recovery method (pumping using conventionalwell recovery methods, gravity drain or thermal methods, typically usingsteam or diluent to mobilize a heavy oil or bitumen. In addition, thepossibility of secondary and other tertiary recovery methods may beconsidered). From this analysis, the recovery factor can be estimated1907 which, when multiplied by the barrels-of-oil-in-place estimateyields the recoverable barrels. A next step 1905 is to determine thesurface restrictions that affect installation of surface facilities (forexample, storage tanks, equipment storage areas, offices, steamgenerating facilities in the case of a thermal recovery operation). Ascan be appreciated, some or even all of these facilities can beinstalled underground if surface restrictions are too severe. If not,then the surface facilities are designed 1906. The next step 1908 is toobtain geotechnical data for the ground between the surface and thereservoir and any ground around the reservoir. This data is required todesign the method of underground access (shaft or decline). This data1908 along with that the method of recovery established in step 1904 maybe used to determine if the underground drilling workspace should beinstalled in the reservoir, below the reservoir or above the reservoir1909. For example, the drilling workspace would be sited below thereservoir for a gravity drain operation or a thermal recovery operation,inside the reservoir if a cold heavy oil recovery operation in a sandreservoir or above the reservoir for a conventional well recoveryoperation if the geology were preferable to that inside or below thereservoir (for example, if the formation below the reservoir was mixedground with mobile gas or water aquifers). In step 1910, the decision ismade to access the reservoir by shaft (S) or decline (D). For example, ashaft may be selected for moderately deep reservoirs while a decline maybe appropriate for shallower reservoirs or for reservoirs with surfacerestrictions requiring a more distant surface entry point. If a shaftaccess (S) is selected the method of shaft installation is thendetermined in step 1911. This may be a shaft sunk be any of thewell-known shaft sinking methods where workers may operate in the shaftor it the shaft may be drilled by a large drill and circulating mudmethod where ground stability is a concern. In step 1912 the shaft isdesigned. If a decline entry (D) is selected then the decline isdesigned 1914. As can be appreciated, underground access may be designedusing both a shaft and decline. Steps 1913 and 1915 lead to the nextlevel of design for the selected entry method.

FIG. 20 is a flow diagram designing the selected method of access forunderground recovery of hydrocarbons. For a shaft access 2001, the firststep is to design the selected method of shaft installation 2002. Adetermination is made in step 2003 whether the shaft is expected to gothrough unstable ground or ground that may contain zones of mobilefluids. If the shaft is expected to go through ground that may containmobile fluids, then the shaft would be drilled Y with no manned entry2005 required until the shaft and its lining is completed. If the shaftis expected to go through stable ground N, then it can be sunk byconventional shaft sinking methods where workers are permitted in theshaft during construction 2006. If there are a number of pay zones thatare to be drilled, then the number of working platforms in the shaft aredetermined in step 2006. The shaft utilities are designed in step 2007(elevators, ventilation, electrical, pipelines, pumps etc). Theprocedures for designing a decline access are similar to those of theshaft procedure. If unstable ground is anticipated, a slurry TBM orother method such as NATM may be used 2015 to install a liner throughthese zones. Otherwise the decline can be installed using 2014 by othermethods such as unpressurized TBMs, roadheaders, drill&blast or thelike.

FIG. 21 is a flow diagram for selecting 2101 a location for drillinglocations for underground recovery of hydrocarbons. If the selectedrecovery method 2102 is gravity drain 2104, then the drilling rooms arealmost always sited under the reservoir 2106. If the selected recoverymethod is thermal 2103, then the drilling rooms are usually sited underthe reservoir 2106 to avoid overheated from steam, for example, injectedinto the reservoir to mobilize a heavy oil or bitumen resource. If theselected recovery method is cold recovery method 2105, then the drillingrooms may be sited below 2107, inside 2108 or above 2109 the reservoirdepending on geology of the formations (especially those with mobile gasor aquifers) and on the type of water or gas flood that may have to beused to increase production. Once the drilling room sites are selected,the drilling patterns may be laid out 2111. If shaft access is planned,then the number of drilling levels are determined 2112 and the number ofdrilling well head sites are selected 2114 for each level 2113. Adrilling well head site is a location where the drill head equipmentsuch as blow out preventers are installed. As described in FIG. 8,several wells can be drilled from a single well head site. The selectedmethod 2115 of forming the workspace for each drill head site may bedifferent for each level or may be different at the same level. If adecline access is planned, then the selection of drilling well headsites 2116 and selection of drilling workspace method 2117 is somewhatsimpler because the decline access is generally only to a single payzone level.

FIG. 22 is a flow diagram for selecting a workspace type for drillingfor underground recovery of hydrocarbons 2201. If the access is byshaft, then well head placement 2203 may be directly through the shaftliner 2207 (for example if only a few wells are planned); well headrecesses (such as shown in FIGS. 2 through 6) may be installed 2206 sothat more space is available so that wells can be installed; a drillingroom may be installed 2205; or a tunnel may be driven from the shaft2204 into the formation. As pointed out previously, a tunnel isessentially a very long drilling room and is usually formed by differentmethods. If the access is by decline, drilling rooms can be installedfrom the decline 2212 or a tunnel can be driven below, into or above thereservoir 2213. Well heads may be established through the tunnel liner2216; well head recesses may be installed 2215; or a drilling room maybe installed 2214. As can be appreciated, any combinations ofestablishing well head work spaces may be used.

FIG. 23 is a flow diagram for selecting a workspace method for drillingfrom a shaft for underground recesses can be installed through thetunnel liner 2313 (recesses are necessary to avoid protruding well headequipment into the tunnel) or drilling rooms can be installed fromvarious locations along the tunnel 2302. Several methods are availablefor installing drilling rooms through a shaft or tunnel liner. All ofthese methods are capable of being used when there is formation pressureor fluids in the ground where the drilling rooms are to be located. Oneselection is ground modification 2303 wherein the ground is frozen toprovide temporary ground stability until the excavation can be lined,for example with shotcreting or installing a concrete or metal liner.Another selection is to form a drilling room excavation using ahorizontal secant pile method 2304 such as described in FIGS. 16 and 17.Yet another selection is to form a drilling room excavation usingrobotic technology such as described in FIGS. 11 through 15. Yet anotherselection is to form a drilling room excavation using the well knownNATM method 2306 adapted if necessary for soft ground. Yet anotherselection is to form a drilling room excavation using well known soilmixing techniques 2307 to form a volume of ground with higher strengththan the in-situ material. This is a less preferred method if thedrilling rooms are to be installed in the hydrocarbon formation and maybe better suited to install drilling rooms in the formations above orbelow the reservoir. Yet another selection is to form a drilling roomexcavation using hydraulic mining methods 2308 such as described byJohns in U.S. Pat. No. 4,076,311 or as disclosed by the presentinventors in U.S. Provisional Patent Application 60/867,010. Ifhydraulic mining methods are used, the mined volume may have to bebackfilled with a concrete so that a drilling room can be safelyexcavated within the volume of concrete. Once a drilling room has beenexcavated, well head equipment can be installed through the lined drillroom walls or recesses such as described in FIGS. 2 through 7. Thereupondrilling producer, injector, sequestering or water management wells canbegin.

FIG. 24 is a flow diagram for selecting a workspace method for drillingfrom a decline for underground recovery of hydrocarbons. This procedureis nearly identical to that described in FIG. 23 where a tunnel isdriven from the access decline and drilling rooms are installed from thetunnel by all the methods that can be used from a shaft access.

FIG. 25 is a schematic representation of a computerized process forimplementing the example decision process shown in FIGS. 18 through 24.FIG. 25 shows a computer 2501 comprised of an input 2503 which may befor example, a keyboard, a touch screen, mouse, a stylus or the like, anoutput 2502 which may be for example, printout, transmittable files,plots and the like, computer memory 2504 which may include storage onmemory chips, hard drives, CD-ROMs and the like, and computerprocessor(s) 2505. The computer 2510 is directed by a software program2521 which is typically implemented by processor(s) 2505. The softwareprogram 2521 acts on various data bases that may be input 2503 into thecomputer memory 2504. Data bases may include, for example, geologicaldata on the hydrocarbon deposits 2511; geotechnical data on theoverburden, hydrocarbon deposits and basement formations; reservoir dataon the hydrocarbon producing zones 2513; production data 2514;regulatory requirements 2515; infrastructure data 2516; excavationmethod data 2517; other installation data 2518 and market data 2519. Thesoftware 2521 utilized these and other data bases to execute a selectionalgorithm such as described, for example in FIGS. 18 through 24. As canbe appreciated, such a program can be of valuable assistance to thosedeveloping a plan to install and operate an underground hydrocarbonrecovery facility.

FIG. 27 is a schematic side view of wellhead control equipment installedin a tunnel or shaft liner and provides a close up cutaway side view ofa tunnel liner wall 2707 with well-head equipment 2703 installed. Thewell-head equipment 2703 is attached and sealed to the tunnel liner2707. Well-head equipment 2703 is secured, for example, to a flange 2704pre-cast into the tunnel liner wall 2707. A portion of the well-headequipment 2703 is set into the formation 2705. As shown, that portion istypical of well-production operations and collects hydrocarbons anddelivers them to a piping system 2706. The equipment shown is a wellheadcontrol assembly which includes blow-out preventers. Equipment such asthis allows drilling, logging, casing and servicing of wells to becarried out while the interior workspace is fully sealed from theformation. A drill rig can be used with well-head equipment as shown inFIG. 27 to initiate and complete a well while maintaining a seal betweenthe interior workspace and the formation.

FIG. 28 illustrates features of tunnel liner sealing. A soft-groundtunnel liner is commonly comprised of short cylindrical liner sections.The sections are in turn comprised of segments. Alternately, a tunnelliner may be formed by continuously extruding a concrete liner, a newermethod that does not require as much sealing as a liner assembled fromsegments and sections. An end view of a typical tunnel liner is shown inFIG. 28 a showing three segments 2801 joined together at joints 2802which may include sealing gaskets (not shown) and may be bolted 2803.The segments are typically pre-cast and made from a high strengthmaterial such as for example concrete or fibre-reinforced concrete. Anadditional optional sealing liner 2804 may be installed to provideadditional sealing. This sealing liner may be made of rubber, urethaneor another tough sealing material. A side view of the tunnel liner isshown in FIG. 28 b illustrating two sections 2810 of outer diameter 2813joined together by a joint 2811. A longitudinal segment joint 2812 suchas described in FIG. 28 a is also shown. Once each section 2810 isassembled inside the TBM shield, it is compressed against the previouslyinstalled section by the action of the TBM propelling itself forward byits hydraulic rams against the end of the tunnel liner. A seal is formedat section joints 2811 by a sealing gasket such as shown in FIG. 28 cwhich illustrates a close-up section view between two liner sections2820 and their joint surfaces. Typically a sealing gasket mountingassembly 2821 is cast into the liner segments 2820. A compressiblesealing material 2822 is installed in at least one of the sealing gasketmounting assemblies 2821. When the liner sections 2820 are compressed bythe propelling action of the TBM, the sealing material 2822 iscompressed forming a seal between adjacent tunnel liner sections.

Once a lined shaft or lined tunnel is installed, wells can be drilledthrough the shaft or tunnel wall liners by first attaching a wellheadcontrol assembly (used for drilling, logging, operating and servicingwells, for example, at the well-head of a surface-drilled well) and thenusing this assembly to drill through the liner wall while maintaining aseal between the formation from the inside of the shaft or tunnel lineras illustrated for example in FIG. 27. This is also a well-knownpractice.

The present invention includes a method of recovering hydrocarbons bydeveloping an underground workspace that is isolated from the formationboth during installation and operations. This requires means of sealingthe excavating machines, drilling machines, and working spaces at alltimes. The principal points of sealing include that between the shaftwalls and the formation. Beginning a tunnel from a shaft is knownpractice. The shaft wall must be thick enough that the TBM can be sealedinto place before it actually starts to bore.

There are other advantages of the present invention not discussed in theabove figures. For example, the logic embodied in FIGS. 18 through 24can be implemented by an automated computer program, manually or acombination of both methods.

A number of variations and modifications of the invention can be used.As will be appreciated, it would be possible to provide for somefeatures of the invention without providing others. The presentinvention, in various embodiments, includes components, methods,processes, systems and/or apparatus substantially as depicted anddescribed herein, including various embodiments, sub-combinations, andsubsets thereof. Those of skill in the art will understand how to makeand use the present invention after understanding the presentdisclosure. The present invention, in various embodiments, includesproviding devices and processes in the absence of items not depictedand/or described herein or in various embodiments hereof, including inthe absence of such items as may have been used in previous devices orprocesses, for example for improving performance, achieving ease and\orreducing cost of implementation.

The foregoing discussion of the invention has been presented forpurposes of illustration and description. The foregoing is not intendedto limit the invention to the form or forms disclosed herein. In theforegoing Detailed Description for example, various features of theinvention are grouped together in one or more embodiments for thepurpose of streamlining the disclosure. This method of disclosure is notto be interpreted as reflecting an intention that the claimed inventionrequires more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive aspects lie in less than allfeatures of a single foregoing disclosed embodiment. Thus, the followingclaims are hereby incorporated into this Detailed Description, with eachclaim standing on its own as a separate preferred embodiment of theinvention.

Moreover though the description of the invention has includeddescription of one or more embodiments and certain variations andmodifications, other variations and modifications are within the scopeof the invention, e.g., as may be within the skill and knowledge ofthose in the art, after understanding the present disclosure. It isintended to obtain rights which include alternative embodiments to theextent permitted, including alternate, interchangeable and/or equivalentstructures, functions, ranges or steps to those claimed, whether or notsuch alternate, interchangeable and/or equivalent structures, functions,ranges or steps are disclosed herein, and without intending to publiclydedicate any patentable subject matter.

1. An excavation method, comprising: (a) providing a substantiallyvertically inclined shaft, at least a portion of the substantiallyvertically inclined shaft being lined to inhibit entry, into an interiorof the at least a portion of the substantially vertically inclinedshaft, of a formation fluid from a hydrocarbon-containing formation; (b)at a selected level of the at least a portion of the substantiallyvertically inclined shaft, forming, while maintaining a pressure andfluid seal between the shaft interior and the formation, a plurality ofrecess cavities extending approximately radially outward from the atleast a portion of the substantially vertically inclined shaft, theselected level being adjacent to or near a hydrocarbon-containingformation; and (c) drilling, while maintaining a pressure and fluid sealbetween the at least a portion of the substantially vertically inclinedshaft interior and the formation to inhibit entry of the formation fluidinto the shaft interior, at least one well outward from a face of eachof the recess cavities, the at least one well penetrating at least aportion of the hydrocarbon-containing formation and wherein the seal ismaintained continuously during the duration of formation and operationof the at least one well. 2.-3. (canceled)
 4. The method of claim 1,wherein the drilling step (c) comprises: (c1) from the at least aportion of the substantially vertically inclined shaft, drilling througha flange positioned adjacent to a surface of the at least a portion ofthe substantially vertically inclined shaft to form a drilled holeextending outwardly from the at least a portion of the substantiallyvertically inclined shaft; (c2) placing a cylindrical shield in thedrilled hole; (c3) securing the shield to the surface of the at least aportion of the substantially vertically inclined shaft; and (c4)introducing a cementitious material into, an end of the drilled hole toform a selected recess cavity, wherein, when the cementitious materialsets, the set cementitious material and shield will seal the interior ofthe cavity from formation fluid.
 5. The method of claim 1, wherein thedrilling step (c) comprises: (c1) from the at least a portion of thesubstantially vertically inclined shaft, drilling, by a drill stem andbit, through a flange and sealing gasket, the flange and gasket beingpositioned on a surface of the at least a portion of the substantiallyvertically inclined shaft, to form a drilled hole extending into thehydrocarbon-containing formation; (c2) while the hole is being drilledextending a cylindrical shield into the hole in spatial proximity to thedrill bit, the shield surrounding the drill stem; (c3) pumping acementitious composition through the drill stem and into a bottom of thedrilled hole; (c4) securing the shield to the flange; and (c5) after thecementitious composition has set, removing the drill stem from the holeto form a selected recess cavity, wherein, when the cementitiousmaterial sets, the set cementitious material and shield will seal theinterior of the cavity from formation fluid.
 6. The method of claim 1,wherein the forming step comprises: stabilizing thehydrocarbon-containing formation by ground freezing and/or soil mixing;while the formation is stabilized, drilling the recess cavity into theformation; and installing a liner to seal the recess cavity interiorfrom the formation.
 7. (canceled)
 8. The drilling method of claim 1,wherein the drilling step (c) comprises: (C1) from the at least aportion of the substantially vertically inclined shaft, drilling througha flange positioned adjacent to a lined surface of a selected recess toform a drilled hole extending outwardly from the at least a portion ofthe substantially vertically inclined shaft; (C2) placing a cylindricalshield in the drilled hole; (C3) securing the shield to the linedsurface of the excavation; and (C4) introducing a cementitious materialinto an end of the drilled hole to form a selected recess cavity,wherein, when the cementitious material sets, the set cementitiousmaterial and shield will seal the interior of the hole from formationfluid of the hydrocarbon-containing formation.
 9. The method of claim 8,wherein, in the drilling step (C1), a drill stem and attached bit, drillthrough a flange and the sealing gasket, the flange and gasket beingpositioned on the at least a portion of the substantially verticallyinclined shaft surface and wherein the drilled hole extends into ahydrocarbon-containing formation.
 10. The method of claim 8, wherein,during the drilling step, (a) a cylindrical shield is extended into thehole in spatial proximity to the drill bit, the shield surrounding thedrill stem.
 11. The method of claim 10, wherein the shield rotates inresponse to rotation of the bit. 12.-24. (canceled)
 25. An excavationmethod, comprising: (a) providing a substantially vertically inclinedshaft, at least a portion of the substantially vertically inclined shaftbeing lined to inhibit entry, into an interior of the at least a portionof the substantially vertically inclined shaft, of a formation fluidfrom a hydrocarbon-containing formation; (b) at a selected level of theat least a portion of the substantially vertically inclined shaft,forming, while maintaining a pressure and fluid seal between the atleast a portion of the substantially vertically inclined shaft interiorand the formation, a plurality of recess cavities extendingapproximately radially outward from the at least a portion of thesubstantially vertically inclined shaft, the selected level of the atleast a portion of the substantially vertically inclined shaft beingadjacent to or near a hydrocarbon-containing formation, wherein each ofthe recess cavities has a diameter ranging from about 1 to about 2meters and a length ranging from about 4 to about 10 meters; and (c)drilling, while maintaining a pressure and fluid seal between the atleast a portion of the substantially vertically inclined shaft interiorand the formation to inhibit entry of formation fluid into the shaftinterior, at least one well outward from a face of each of the recesscavities, the at least one well penetrating at least a portion of thehydrocarbon-containing formation and wherein the formation fluid seal ismaintained continuously during the duration of formation and operationof the at least one well.
 26. The method of claim 25, wherein the recesscavities are lined with a formation fluid impervious liner, wherein theat least a portion of the substantially vertically inclined shaftcomprises one or more spaced apart levels, and wherein each of the oneor more spaced apart levels comprises a plurality of approximatelyradially outwardly extending recess cavities.